Petroleum products



PETROL Ice L. Fra

u E. to Standard Oil poration of No Brag.

The present invention relates to improvements in the art of alkyl'atingoleflns with isoparamns and more particularly it relates to thealkylation of olefins with isoparafiins in the presence of sulfuric acidcatalyst, in which process the last traces of sulfuric acid, either incombined form or in solution, are substantially completely removed fromthe finished allrylate.

In allrylating an olefin with an isopa-rafin, for example butylene withisobutane in the presence of strong sulfuric acid such as acid having astrength of from about 95% to 98% and at-the usual temperatures, say inthe neighborhood of 35" E1, the usual practice employed in recoveringthe allrylate from the reaction zone is to disv charge the "emulsionconsisting of sulfuric acid,

allrylate; unreacted isoparaffih, etc., into a settling zone; theemulsion is then permitted to stratify in said settling zone into anupper hy drocarbon layer containing the alkylation prodnot or alkylate,as it is often. called, and a lower sulfuric acid layer. The upper layeris drawn ed and purified by washing, neutralising and distilling torecover the desired finished alkylate.

However, it has been found that the most care- Development iomp a r-Application my 28, 1942, s No. 452,559

to produce an alkylation product which may he distilled in ordinaryplant or other metallic dis tillation equipmentdncluding transfer pipes,heat exchangers, reboilers, condenser coils and the like without causingcorrosion and/or fouling of said equipment.

A further object of my present invention is to render a branched chainparamn hydrocarbon, produced from an isopara and an olefin in thepresence of an acid catalyst such as sulfuric, noncorrosive' towardmetallic surfaces which it may contact for extended periods of time atelevated temperatures such as are encountered in the distillation of theallrylation product.

Other and further objects of myinvention will appear from the followingmore detailed descrip- 'tion and claims.

Tests have shown that the decomposition of the corrosion formingmaterials in the allrylate can be retarded or, in some instances,completely eliminated by adding to the alkylate a small quantity of ahydrocarbon-soluble base such as an aliphatic or aromatic amine. Thetests were made by flash vaporizing, at atmospheric temperatures, thebutane from an alkylate and addful washing with caustic soda solutionand/or water has heretofore failed to remove from the product acidicsubstances formed in the reaction or present during it. Hence when thewashed and caustic soda treated alkylation product was distilled toseparate the C4 and C5 hydrocarbons including butanes and isopentane,the distillation process resulted in fouling and corrosion ofdistillation equipment. The careful washing and/or caustic sodatreatment of the raw alkylation product had little or no effect inpreventing corrosion and/or fouling of the equipment during thedistillation of the said alkylate.

I have now observed that in the alkylate there are sulfuric acid estersor other acidic compounds and that these apparently pass through and arenot removed during washing and/or treatment of the alkylate with acaustic soda solution or an equivalent alkaline reacting substance. Inany event there is probably present in the alkylate product, prior toand during distillation, derivatives of sulfuric acid. Tests indicatethat these derivatives undergo decomposition during the distillationliberating. acid reacting substances, and it is believed that theselatter substances are responsible for the difficulties experienced inplant distillation of thealkylate or alkylation products.

ing 0.001 to 0.04 volume per cent of the base to the debutanizedalkylate. Samples of the inhibited and uninhibited alkylates were thenheated to temperatures comparable to those experienced in commercialplant reboilers and preheaters or to a maximum of 400 F. (ii fouling didnot occur at normal plant temperatures), and oleservations were made ofthe temperature at which formation of S02 and fouling deposit began. Theresidue remaining after heating to 400 F. was tested for acidity andsulfate ion. The experiments indicated that a minimum of 0.001 volumeper cent or a maximum of 0.01 volume per cent was desirable forreduction or elimination of the decomposition during heating. The

above quantities are the most desirable, but it is The main object of mypresent invention is possible to use quantities ranging from 0.001 to0.1 volume per cent. The experimental results are presented in thefollowing examples:

mimnn m Warn Wnsm m 'I'ssrsn BY Karma is Guss the finished alkylate maycauseprecipitation or lead compounds, particularly in storage or in 5transit, where lead tetraethyl is added to an alkylate-containingaviation gasoline or automotive u ie- 38%. m fmfi fuel. Md Although thedescription given with respect to the examples or my invention indicatesthat the rmmmmpmmm m wf ils, at amine was added after debutanlzation ofthe raw alkylation product, I wish to make it clear that EXAM? the aminemay be added at-any point in'the op- LE m eration after the alkylate hasbeen separated Asmara Drsrmimznn, Curs'rrc Sons Sonurron {mm thealkymtion catalyst and prior to any g m i' l5 distillation step wherecorrosion and/or fouling +Aniline +Triamylamlns .01 0.00:: 533 ul z11012; sligl l 'rouunztem mmwr- 200 M32!) At295 Atrso Maze A t325EXAMPLE IV may occur. Preferably, I separate the raw alkylate from thealkylation catalyst, wash the g ggggg jgggggigg g, alkylate with adilute alkaline solution and with EQUIPMENT WITH AND WITHOUT STEAM Inmmwater, and then I mix the amine with the separron rated alkylate beforesubjecting the mixture to Dr distillation debutanization anddistillation. Addition of the amine before the washing step is notdesirable I since this class of compounds is generally soluble inhibitedtmmmmlamme in water and would be removed from the alkylate an 80 m Sm!so m 35 during the washing operation.

szm h 3 sun Now while it appears that the underlying cause 5333 i lii titif i. tillate of the corrosive tendency of alkylate produced in thepresence of aniacid catalyst is due to the 200 No No. a presence of acidesters in the said alkylate, I do Egg g??- 40 not wish to be bound byany theories regarding m the cause of the corrosive nature of thealkylate but shall rely on the observed facts hereinbefore st i t t setforth particularly as to the results I have accomplished in theprevention or retardation of corrosion and/or fouling of distillationequip-. U inhb d .01 ur m lamln n I +0 7 8 am e ment during theprocessing, particularly the final mm 80am 8m} Sm] 80am still stagesthereof, of alkylation products. Furthertemperathe an fouled temperstheidis- {medmore, my improvements are applicable to correct m or atleast ameliorate the corrosive and fouling N tendencie of branched chainparafilnic hydro- $3513: $2511: 333 $3533: Slight carbons whether theybe produced in the m 310 Yes 390 Yes..... Do. ence of sulfuric acidalone, admixed with other was appreciable at 260 F. and became heavieras distillation continued.

It will be noted from the above test that the addition of an aminerendered the alkylate product (which was that made by reacting isobutaneand butylene in the presence of sulfuric acid) passive toward metallicdistillation equipment or atleast retarded the corrosive and foulingtendency of the said alkylate.

The importance of this invention will be apparent when it is realizedthat, in operating a iractionating column for the debutanization anddistillation of an alkyiate, the temperatures which are reached invarious parts of the equipment, such as reboilers, heat exchangers, andthe like, are often of the order of 400 F. or higher, and theseconditions are conducive, to say the least, toward decomposition ofesters of sulfuric acid and/or other acid-containing bodies to liberatesubstances of a corrosive nature. Obviously, this is a serious problemsince it usually causes both substances such as HBPO4, P205, HCl, NiSOior whether the acid catalyst be anacid other than sulfuric acid such asHCI, HF, I'ISPOi, or whether it be catalysts such as P205, BF: and H20,or the like. 01 course, strong sulfuric acid is the most satisfactorycatalyst for isobutane-butylene alkylation, all factors considered, andthis is true also for the alkylation of normally liquid olefins.

To review briefly, my present invention is directed toward immunizingmetallic equipment against corrosion and fouling when it is con tactedwith raw alkylate, comprising the reaction product of isoparafins andoleflns produced in the presence of an acid catalyst, by adding to thealkaliand water-washed raw alkylate (after removal of the washing and/ortreating agent) a small quantity of an aromatic-, an aliphaticor analkanol-amine. I may use for this purpose any amine which is solubleeven slightly in the said alkylate.

I wish to include within the scope of the appended clair'ns all subjectmatter expressly disclosed herein and included also by reasonableinference, excluding only that required by the terms of the appendedclaims.

What I claim is:

1. In the treatment of alkylate product obtained by reacting an olefinand an lsoparaflln in the presence of an acid catalyst including thesteps of separating the alkylate product from the catalyst,neutralizing, and water washing and subsequently subjecting the alhlateto a distillation step, the step of rendering the alkylate non-corrosiveto metal which comprises the step of adding a small quantity of an amineto l0 debutanized alkylate.

the neutralized water washed alkylate prior to the distillation step.

2. The process specified in claim 1 in which the amine is aromatic. v

3. The process as set forth in claim 1 in which the amine is aliphatic.

4. The process as set forth in claiml in which the quantity of amineisin the range between 0.001 and 0.1 volume per cent based on the JOE L.FRANKLIN, JR.

